User talk:Penguin5678990

April 2013
Hello, I'm Christian75. I wanted to let you know that I undid one of your recent contributions, such as the one you made with this edit to Analytical chemistry, because it didn’t appear constructive to me. If you think I made a mistake, or if you have any questions, you can leave me a message on my talk page. Thanks, Christian75 (talk) 15:08, 5 April 2013 (UTC)